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The colonization history of largely isolated habitats
Andrea Meseguer
To cite this version:
Andrea Meseguer. The colonization history of largely isolated habitats. Peer Community in
Evolu-tionary Biology, Peer Community in, 2019, pp.100065. �hal-01969659�
Open Access
RECOMMENDATION
The colonization history of largely
isolated habitats
Andrea S Meseguer
1Cite as: Meseguer AS. The
colonization history of largely isolated habitats.Peer Community In
Evolutionary Biology, 100065 (2019).
DOI: 10.24072/pci.evolbiol.100065
Published: 02nd January 2019
Based on reviews by:
Florian Boucher, Simon Joly and two anonymous reviewers
Correspondence:
asanchezmeseguer@gmail.com
CC-BY-ND 4.0 This work is licensed under the Creative Commons
Attribution-NoDerivatives 4.0 International License.
1CNRS, UMR 5554 Institut des Sciences de l’Evolution (ISEM), Univ Montpellier – Montpellier,
France
A recommendation of
Pirie MD, Kandziora M, Nuerk NM, Le Maitre NC, Kuppler ALM de, Gehrke B, Oliver EG, and
Bellstedt DU. Leaps and bounds: geographical and ecological distance constrained the colonisation of the Afrotemperate by Erica.bioRxiv 290791, ver. 5 peer-reviewed and recommended by PCI Evol Biol (2018).DOI: 10.1101/290791
The build-up of biodiversity is the result ofin situ speciation and immigration, with the interplay between geographical distance and ecological suitability determining the probability
of an organism to establish in a new area. The relative contribution of these factors have
long interested biogeographers, in particular to explain the distribution of organisms adapted
to habitats that remained largely isolated, such as the colonization of oceanic islands or
land waters. The focus of this study is the formation of the afrotemperate flora - patches
of temperate vegetation separated by thousands of kilometers in Africa, with high levels of
endemism described in the Cape region, the Drakensberg range and the high mountains
of tropical east Africa [2]. The floristic affinities between these centers of endemism have
frequently been explored but the origin of many afrotemperate lineages remains enigmatic [1].
To identify the biogeographic history and drivers of biogeographic movements of the large
afrotemperate genusErica, the study of Pirie and colleagues [3] develops a robust hypothesis-testing approach relying on historical biogeographic models, phylogenetic and species
occur-rence data. Specifically, the authors test the directionality of migrations through Africa and
address the general question on whether geographic proximity or climatic niche similarity
constrained the colonization of the Afrotemperate byErica. They found that the distribution of Erica species in Africa is the result of infrequent colonization events and that both geographic proximity and niche similarity limited geographic movements (with the model that
incorpo-rates both factors fitting the data better than null models). Unfortunately, the correlation
between geographic and environmental distances found in this study limited the potential
evaluation of their roles individually. They also found that species ofErica have dispersed from Europe to African regions, with the Drakensberg Mountains representing a colonization
sink, rather than acting as a “stepping stone” between the Cape and Tropical African regions.
Advances in historical biogeography have been recently questioned by the difficulty to
com-pare biogeographic models emphasizing long distance dispersal (DEC+J) versus vicariance
(DEC) using statistical methods, such as AIC, as well as by questioning the own performance of
DEC+J models [4]. Behind Pirie et al. main conclusions prevails the assumption that patterns
of concerted long distance dispersal are more realistic than vicariance scenarios, such that
a widespread afrotemperate flora that receded with climatic changes never existed. Pirie
et al. do not explicitly test for this scenario based on the idea that these habitats remained
largely isolated over time and our current knowledge on African paleoclimates and vegetation,
emphasizing the value of arguments based on empirical (biological, geographic)
considera-tions in model comparisons. I, however, appreciate from this study that the results of the
biogeographic models emphasizing long distance dispersal, vicariance, and the unconstrained
models are congruent with each other and presented together.
Pirie and colleagues [3] bring a nice study on the importance of long distance dispersal
and biome shift in structuring the regional floras of Africa. They evidence outstanding
ex-amples of radiations inErica resulting from single dispersal events over long distances and between ecologically dissimilar areas, which highlight the importance of niche evolution
and biome shifts in the assembly of diversity. Although we still face important limitations
in data availability and model realism, the last decade has witnessed an improvement of
our understanding of how historical and environmental triggers are intertwined on shaping
biological diversity. I found Pirie et al.’s approach (and analytical framework) very stimulating
and hope that will help movement in that direction, providing interesting perspectives for
future investigations of other regions.
References
[1] Galley C, Bytebier B, Bellstedt DU, and Peter Linder H. The Cape element in the
Afrotem-perate flora: from Cape to Cairo?Proceedings of the Royal Society B: Biological Sciences 274 (2006), 535–543.DOI: 10.1098/rspb.2006.0046.
[2] Linder H et al. On the relationship between the vegetation and floras of the
Afromon-tane and the Cape regions of Africa.Mitteilungen aus dem Institut für Allgemeine Botanik Hamburg (1990), 777–790.
[3] Pirie MD, Kandziora M, Nuerk NM, Le Maitre NC, Kuppler ALM de, Gehrke B, Oliver EG,
and Bellstedt DU. Leaps and bounds: geographical and ecological distance constrained
the colonisation of the Afrotemperate by Erica.bioRxiv 290791, ver. 5 peer-reviewed and recommended byPCI Evol Biol (2018).DOI: 10.1101/290791.
[4] Ree RH and Sanmartín I. Conceptual and statistical problems with the DEC+ J model of
founder-event speciation and its comparison with DEC via model selection.Journal of Biogeography 45 (2018), 741–749.DOI: 10.1111/jbi.13173.
Appendix
Reviews by Florian Boucher, Simon Joly and two anonymous reviewers,
DOI: 10.24072/pci.evolbiol.100065
